BoilerFaultCodesPotterton Lockout (Red) On Fault Code
Also written as LOCKOUTREDON — same fault.
The Potterton Lockout (Red) On fault code means: your boiler has tried and failed to light the flame several times, so it has shut itself down for safety.. It appears on 1 Potterton model in our database.
Technical description: Ignition LOCKOUT - After five attempts (possibly due to air in the gas supply) it will lockout
What causes the Potterton Lockout (Red) On fault?
This fault occurs when the boiler cannot detect a stable flame after several attempts to fire up. It is often caused by a lack of gas reaching the burner, a worn-out spark electrode that can no longer create a light, or a dirty sensor that fails to tell the boiler the flame is actually lit.
This issue can occur more frequently during the first cold snap of autumn when components that have been idle all summer suddenly fail under the strain of constant use.
DIY fix possible
Check that your gas meter is turned on and you have credit (if using a prepay meter).Check if other gas appliances, like a hob, are working to confirm gas supply.Turn the selector switch to the 'Reset' position, hold for a few seconds, then release.
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Gas Safe Register →Potterton models that show the Lockout (Red) On fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Potterton Lockout (Red) On fault code information on this page is sourced and cross-checked against the official Potterton service / installation manuals for each affected model.
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026